Listeria innocua M1 has been used by many researchers as a nonpathogenic thermal processing surrogate for Listeria monocytogenes. However, L. innocua M1 has been criticized because its thermal survivability characteristics are not as closely parallel to L. monocytogenes as some would like in a variety of foods and processing conditions. The present study was conducted to compare multiple L. innocua and L. monocytogenes strains to validate L. innocua M1 as the ideal surrogate under high-temperature thermal processing conditions for L. monocytogenes. The D- and z-values of L. innocua M1, L. innocua strain SLCC 5639 serotype (6a), SLCC 5640 (6b), SLCC 2745 (4ab), and L. monocytogenes F4243 (4b) were calculated for raw hamburger patties. Hamburger patties were inoculated with 10(7-8) CFU/g of L. monocytogenes or L. innocua. Samples were heat treated at 4 temperatures (62.5 to 70 degrees C). At each temperature, the decimal reduction time (D-value) was obtained by linear regression of survival curves. The D- and z-values were determined for each bacterium. The D-values of L. innocua and L. monocytogenes serotypes ranged from 3.17 to 0.13 min at 62.5 to 70 degrees C, and the z-values of L. innocua and L. monocytogenes were 7.44 to 7.73 degrees C. Two of the 4 L. innocua serotypes used in this experiment have the potential for use as surrogates in hamburger meat with varying margins of safety. L. innocua M1 should serve as the primary nonpathogenic surrogate with the greatest margin of safety in verifying a new thermal process to destroy L. monocytogenes.

Background and objectives Pulse flours can impart off‐flavors limiting their use in foods. The objective of this study was to examine the flour and bread making properties of whole and split yellow peas treated with dry and steam heat used as a premilling treatment. Findings Particle size distributions and pasting properties of flours milled from heat‐treated peas were altered, and starch damage was reduced compared to flours milled from untreated peas. Breads made with flour milled from heat‐treated peas had similar firmness to breads made with flour milled from untreated peas with no change in volume and minimal impact on crumb structure. Changes in crumb color (lower L*, higher a*) were consistent with color changes observed in the flours. Heat treating whole peas produced breads with decreased aroma, flavor, and aftertaste, whereas heat treating split peas produced breads with lower intensities of aroma, flavor, bitterness, and aftertaste and increased acceptability. Conclusions Revtech dry and steam heating of whole and split yellow peas as a premilling treatment successfully reduced off‐flavors with minimal changes to flour and bread making properties. Significance and novelty Heat treating pulses prior to milling offers greater opportunities for incorporating pulse flours in foods.

The effect of adding fermented split yellow pea flour (SYPF) as a partial replacement for wheat flour in bread was examined. Three sourdough culture levels (3%, 6.5%, and 10%) and two fermentation times (1 and 4 hr) were evaluated. Total titratable acidity of ferment was measured to determine acid development. Bread was baked using three ferment inclusion levels (25%, 35%, and 45%) for each of the six treatment combinations. Nonfermented control bread was baked for each inclusion and culture level by adding the equivalent amount of SYPF and culture to the formulation. Bread was scored for quality and assessed for specific volume, crumb colour, C‐Cell properties, and flavour. Significant main effects were found for inclusion level, culture level, and fermentation time, and a significant Inclusion level × Fermentation time interaction was found for crumb firmness and cell diameter. Breads made with nonfermented SYPF and 10% culture had good flavour with only minor reductions in bread quality compared with a 100% wheat control bread. For the breads made with fermented SYPF, the ferment made with 10% culture fermented for 1 hr and added at an inclusion level of 25% had the most acceptable flavour and bread quality characteristics.

No abstract

Cereal Chem. 94(2):333-340